Silencer for combustion engines

ABSTRACT

A silencer for the exhaust pipe from a combustion engine wherein a jacket attached to and of diameter larger than the pipe encloses a perforated sleeve of relatively smaller diameter providing a space therebetween. A tube inside the sleeve and of diameter smaller than the sleeve forms an annular chamber between them. Tabs punched from the wall of the tube are bent to transverse positions within the tube and, acting with the perforations, form a tortuous path for hot exhaust gases passing from the pipe to the silencer.

I Unlted States Patent 11 1 1111 3,770,081 Martin Nov. 6, 1973 [54] SILENCER FOR COMBUSTION ENGINES 1,295,919 5/1962 France 181/56 4,136 2/1912 Great Britain... 181/60 [75] Inventor. Gene L. Martin, Anaheim, Calif. 415,446 8/1934 Great Britain [81/36 B 7 Assignee: i Inc. Anaheim Calif 273,086 3/1930 Italy 181/55 280,030 11/1930 Italy 181/56 [22] Filed: Oct. 13, 1972 [21] Appl. No.: 299,957 OTHER PUBLICATIONS Related Application Data German Application N0. E7858Ia/46c6, 4/1956, [63] Continuation of Ser. No. 104,078, Jan. 5, 1971, B llflr hmldt abandoned.

52 US. (:1. 181/36 B, 181/47 R, 181/55, 4 Primary Examiner-Richard Wilkinson [81/57, 181/69, 181,70 Assistant Examiner-John F. Gonzales 51 Int. Cl. F01n 3/06 Ammeyvemon Beehler [58] Field of Search 181/36 R, 36 B, 47 R, 181/55-57, 60, 63, 6870, 72

[57] ABSTRACT [56] References Cited UNITED STATES PATENTS A silencer for the exhaust pipe from a combustion en- 984 890 2 1911 Dudderar 181/70X gine wherein a jacket attached and diameter 1,709Z426 4/1929 Beery 181/56 U larger than the pipe encloses a perforated sleeve of rel- 1,816,245 7/1931 Wolford 181/57 atively smaller i r p iding a space therebe- 1,993,397 3/1935 Berg et a1... 181/36 B UX tween. A tubeinside the sleeve and of diameter smaller 2,557,687 6/1951 Rainville 9 Isl/36 B UX than the sleeve forms an annular chamber between X Tabs punched from the wall of the tube are bent x' 5: 2; to transverse positions within the tube and, acting with arx 3,561,562 2 1971 Ignoffo 181/72 x the perforimons' form a .tortuous f for hot exhaust gases passing from the p1pe to the silencer. FOREIGN PATENTS OR APPLICATIONS 579,275 7/1924 France 181/70 6 Claims, 9 Drawing Figures //5 20 1Q ,20 1Q Q o o oo o c ""'\""}""1'- ainlvlwrwrv, QQQQQQGF'" J H ./2Q oooooor Q 7 6 6 7 7 1 222,222,. 1

L18 27 lg 28 PATENIEUunv 5 ms sum 1 or 2 L40 k/B JANE/V702 GENE L Miner/N SILENCER FOR COMBUSTION ENGINES This is a Continuation of Copending Application Ser. No. 104,078 filed Jan. 5, 1971, and now abandoned.

Mufflers and silencers for combustion engines which have been acceptable, primarily on automobiles, for the most part tend to be of such size that they are awkward to use on smaller motor vehicles such as motorcycles and scooters. Such construction, satisfactory from the point of view of muffling and silencing, has also been sufficiently involved to require construction making them somewhat expensive for many uses. Some attempts have been made to provide a compact'inexpensive silencer device such for example as packing portions of the exhaust pipe with fiberglass or steel wool but such materials becasue of being finely divided and somewhat compact tend to become clogged after a period of use causing problems in engine performance and necessitating an unnecessary amount of servicing.

It is therefore among the objects of the invention to provide a new and improved silencer for combustion engines which is of simple, inexpensive sheet metal construction making it relatively easy to build and simple to install, while at the same time being capable of increasing the apparent length of travel and direction of exhaust gases thereby to improve the quietness of operation.

With these and other objects in view, the invention consists of the construction, arrangement, and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a longitudinal sectional view of the invention in one of its forms.

FIG. 2 is a fragmentary longitudinal sectional view on the line 2-2 of FIG. 1.

FIG. 3 is a cross sectional view on the line 33 of FIG. 2.

FIG. 4 is a schematic view showing the relative location of. the silencer with respect to a combustion engine.

FIG. 5 is a longitudinal sectional view on the line 5-5 of FIG. 4 showing the invention in another of its forms.

FIG. 6 is a fragmentary perspective view of the form of invention shown in FIGS. 1, 2 and 3.

FIG. 7 is a fragmentary perspective view similar to FIG.'6 showing a somewhat different arrangement of openings.

FIG. 8 is a fragmentary longitudinal sectional view taken on the line 8-8 of FIG. 7.

FIG. 9 is a fragmentary perspective view of still another form of openings.

In an embodiment of the invention chosen for the purpose of illustration there is shown a silencer indicated generally by the reference character 10 attached at the end of an exhaust pipe 1 l which is connected to a combustion engine 12, as shown in FIG. 4.

To capture hot burned exhaust gas from the exhaust pipe 11 there is provided a tube assembly indicated generally by the reference character 15 and shown in longitudinal section in FIG. 1. The tube assembly consists essentially of an outer tube 16 and an inner tube 17, the outer tube being somewhat longer than the inner tube. Extending throughout the length and circumference of the outer tube 16 is a multiplicity of perforations 18. The inner tube 17 is also provided with holes 19 somewhat larger and differently shaped than the perforations 18. In the form of invention of FIGS. 1, 2 and 3 the holes 19 are formed by punching out sections 20 from the material forming the wall of the inner tube 17, ends 21 of the section 20 having a pointed shape complimentary to the ends of the holes 19. In the embodiment of FIGS. 1, 2 and 3 there are four sections 20 at each of a number of locations throughout the length of the inner tube 17, the sections, and corresponding holes, being spaced circumferentially and equidistant one from another about the inner tube. It is significant also that the sections 20 are short enough so that when they are bent into transverse position across the inside of the inner tube 17, edges 22, 23 are spaced from each other leaving passages between. them, the composite of the passages having the shape of a cross as visible in FIG. 3. Additional passages are provided between adjacent parallel edges 24, 25 of the sections. The holes 19 are on the upstream side of the respective sections 20 and at locations staggered with respect to the locations of the perforations 18.

As shown in FIG. 1 there are expanded ends 26, 27

on the inner tube 17 which are forced into contact with the interior surface of the outer tube 16 so as to provide between the tubes an annular chamber 28, the annular chamber extending throughout the entire portion of the inner tube 17 which contains the holes 19. The open upstream end of the inner tube is therefore of about the same cross sectional area as the area of the outer tube. The length of the inner tube 17 is many times greater than the diameter as is also the length of the outer tube 16, the outer tube 16 being longer and providing a substantial portion of its length at the left end as viewed in FIG. 1, not occupied by the inner tube.

When only the tube assembly 15 is to be employed for silencing purposes the end of the tube assembly where the two tubes join as indicated by the reference character 29 is open so that all of the exhaust gases enter the inner tube directly and then find their way outwardly through the holes 19 as well as passing in a tortuous passage through the interior of the inner tube.

In the form of the invention shown in FIG. 5 there is a jacket 30. At one end 31 the jacket is larger than at the other end 32, thereby providing an annular space 33 which is of width varying from smaller at an extrance end 34 to larger at an exit end 35. At the exit end is a shank 36 which provides for a press fit connection with the adjacent end of the outer tube 16 thereby to mount the tube assembly 15 with respect to the jacket 30. A flared collar 37 provides an expanding exit port 38.

When the device is in the form illustrated in FIG. 5 a transverse baffle 39 is made use of at the end 29 of the tube assembly. In this arrangement hot exhaust gases entering into theannular space 33 at the entrance end 34 first pass into the annular space and from it through the perforations 18 into the annular chamber 28 from which they find their way through the holes 19 into the interior of the inner tube 17 and from which ultimately they find their way to the exit end 35 and exit port 38. l

A slightly different arrangement of holes 40, 41 is shown in FIGS. 7 and 8 wherein holes 40 are offset longitudinally with respect to the holes 41, there being two holes 40 at each location and two holes 41 at each location. The holes 40 are on diametrically opposite sides of an inner tube 17 and the holes 41 also diametrically opposite from each other but removed 90 from the holes 40. By reason of the staggered relationship described, sections 42 punched from the holes 40 also are staggered with respect to sections 43 punched from the holes 41, the arrangement being shown also in FIG. 8.

Still another form of the inner tube 17" is shown in FIG. 9 wherein holes 46 47 have their parallel side edges 48, 49 tilted obliquely with respect to the longitudinal axis of the inner tube 17" as shown in FIG. 9. A bend line 50 along which sections 51 and 52 are bent, being at 90 with respect to the parallel edges 48, 49, is also tilted, causing a corresponding tilt to the positions of the sections 51, 52, thereby to enhance the tortuous path for gases traveling through the inner tube 17".

Constructed as shown, exhaust gases passing through the device tend to be deflected and the deflection increases appreciably the length of their path of travel through the silencer as well as causing such a path to be notably diverted from a direction axial with respect to the tubes. By providing such interference with a straight through flow while at the same time avoiding the building up of back pressure by only partially obstructing the flow, a noteworthy .muffling, quieting and also a cooling effect is accomplished by means of a sheet metal structure which is of simple and'inexpensive form, the assembly being such as to be readily attached to a conventional exhaust pipe as shown in FIG. 4.

While the invention has herein been shown and described in what is conceived to be a practical and effective embodiment, it is recognized that departures may be made therefrom within the scope of 'the invention, which is not to be limited to the details disclosed herein but is to be accorded the fullscope of the claims so as to embrace andy and all equivalent devices. 7

Having described the invention, what is claimed as new in support of Letters Patent is:

1. A silencer for the exhaust pipe of a combustion en gine comprising a hollow cylindrical outer'tube having a length many times greater than its transverse dimension, an inner tube having a length many times greater than its transverse dimension located within the outer tube and having an outside diameter smaller'than the inside diameter of the outer tube, said inner tube having an enlarged upstream end adjacent the engine with i the outside wall in engagement with the inside wall of the outer tube and receptive of all the exhaust flow into the inner tube, said inner tube having an opposite downstream end of substantially the same cross sectional area as the cross sectional area of the upstream end,enlargements at respective upstream and downstream ends of the inner tube being the means for spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween which is clear throughout its length, said outer tube having a multiplicity of perforations therethrough throughout the length of said annular chamber, sections of the wall of said inner tube throughout said annular chamber at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holesin said wall, said holes comprising the means by which an exhuast passing laterally from the innentube reaches the annular chamber, said sections being bent to positions at about a right angle to the long axis of said inner tube and having all portions of said sections spaced from adjacent sections, innermost ends of said sections having locations more than half way between the wall and the longitudinal axis of said inner tube, all of said holes being on the upstream side of the respective section which is punched from the wall forming said hole, whereby to form a tortuous path for travel of gases passing through said tubes.

2. A silencer as in claim 1 wherein said holes are of a size greater than the size of the perforations in said outer tube and at locations staggered with respect to the locations of said perforations.

3. A silencer as in claim 1 wherein there is an exterior imperforate jacket spaced radially outwardly from and surrounding said outer tube whereby to form an annular space therearound and wherein the upstream end of said inner tube is closed and is located clear of said jacket.

4. A silencer as in claim 3 wherein said jacket is greater in diameter at the downstream end than at the upstream end.

5. A silencer for the exhaust pipe of a combustion engine comprising a hollow cylindrical outer tube having a length many times greater than its transverse dimension and having a multiplicity of perforations therein,

an inner tube having a length many times greater than 7 its transverse dimension located within the outer tube and having an outside diameter smaller than the inside diameter of the outer tube, means acting between the outer tube and the inner tube spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween, sections of the wall of said inner tube at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holesin said wall with all of the holes being on the upstream side of each respective section, said sections being bent to positions extending at substantially a right angle transverse to the long axis of said inner tube and having all portions of said sections spaced from adjacent sections and with inner free ends reaching a location more than halfway from the wall of said inner tube to the center, whereby to form a tortuous path for travel of gases, passing through said tubes, an exterior imperforate jacket spaced radially outwardly from and surrounding said outer tube whereby to form an annular space therearound, the upstream ends of the outer and inner tubes having a transverse baffle at the upstream end of each of them, blocking passage through the inner tube and through the annular space therethrough.

6. A silencer for the exhaust pipe of a combustion engine comprising a hollow cylindrical outer tube having a length many times greater than its transverse dimension and having a multiplicity of perforations therein, an inner tube having a length many times greater than its transverse dimension located within the outer tube And having an outside diameter smaller than the inside diameter of the outer tube, means acting between the outer tube and the inner tube spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween, sections of the wall of said inner tube at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holes in said wall, said sections being bent to positions extending at substantially a right angle transverse to the long axis of said inner tube and having all portions of said sections portion of the jacket and having a diameter smaller than adjacent portions of the jacket, the location of the pressed fit being sapced longitudinally downstream from the bent sections nearest thereto and the upstream ends of said tubes being clear of the surrouding wall of said jacket. 

1. A silencer for the exhaust pipe of a combustion engine comprising a hollow cylindrical outer tube having a length many times greater than its transverse dimension, an inner tube having a length many times greater than its transverse dimension located within the outer tube and having an outside diameter smaller than the inside diameter of the outer tube, said inner tube having an enlarged upstream end adjacent the engine with the outside wall in engagement with the inside wall of the outer tube and receptive of all the exhaust flow into the inner tube, said inner tube having an opposite downstream end of substantially the same cross sectional area as the cross sectional area of the upstream end,enlargements at respective upstream and downstream ends of the inner tube being the means for spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween which is clear throughout its length, said outer tube having a multiplicity of perforations therethrough throughout the length of said annular chamber, sections of the wall of said inner tube throughout said annular chamber at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holes in said wall, said holes comprising the means by which an exhuast passing laterally from the inner tube reaches the annular chamber, said sections being bent to positions at about a right angle to the long axis of said inner tube and having all portions of said sections spaced from adjacent sections, innermost ends of said sections having locations more than half way between the wall and the longitudinal axis of said inner tube, all of said holes being on the upstream side of the respective section which is punched from the wall forming said hole, whereby to form a tortuous path for travel of gases passing through said tubes.
 2. A silencer as in claim 1 wherein said holes are of a size greater than the size of the perforations in said outer tube and at locations staggered with respect to the locations of said perforations.
 3. A silencer as in claim 1 wherein there is an exterior imperforate jacket spaced radially outwardly from and surrounding said outer tube whereby to form an annular space therearound and wherein the upstream end of said inner tube is closed and is located clear of said jacket.
 4. A silencer as in claim 3 wherein said jacket is greater in diameter at the downstream end than at the upstream end.
 5. A silencer for the exhaust pipe of a combustion engine comprising a hollow cylindrical outer tube having a length many times greater than its transverse dimension and having a multiplicity of perforations therein, an inner tube having a length many times greater than its transverse dimension located within the outer tube and having an outside diameter smaller than the inside diameter of the outer tube, means acting between the outer tube and the inner tube spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween, sections of the wall of said inner tube at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holes in said wall with all of the holes being on the upstream side of each respective section, said sections being bent to positions extending at substantially a right angle transverse to the long axis of said inner tube and having all portions of said sections spaced from adjacent sections and with inner free ends reaching a location more than halfway from the wall of said inner tube to the center, whereby to form a tortuous path for travel of gases passing through said tubes, an exterior imperforate jacket spaced radially outwardly from and surrounding said outer tube whereby to form an annular space therearound, the upstream ends of the outer and inner tubes having a transverse baffle at the upstream end of each of them, blocking passage through the inner tube and through the annular space therethrough.
 6. A silencer for the exhaust pipe of a combustion engine comprising a hollow cylindrical outer tube having a length many times greater than its transverse dimension and having a multiplicity of perforations therein, an inner tube having a length many times greater than its transverse dimension located within the outer tube And having an outside diameter smaller than the inside diameter of the outer tube, means acting between the outer tube and the inner tube spacing said tubes substantially equidistant from each other and forming an annular chamber therebetween, sections of the wall of said inner tube at locations spaced circumferentially and longitudinally from each other being punched from said wall of the inner tube forming holes in said wall, said sections being bent to positions extending at substantially a right angle transverse to the long axis of said inner tube and having all portions of said sections spaced from adjacent sections and with inner free ends at a location closer to the longitudinal axis than to the wall of the inner tube, whereby to form a tortuous path for travel of gases passing through said tubes, an exterior imperforate jacket spaced radially outwardly from and surrounding said outer tube whereby to form an annular space therearound, the downstream end of the outer tube having a pressed fit within a downstream portion of the jacket and having a diameter smaller than adjacent portions of the jacket, the location of the pressed fit being sapced longitudinally downstream from the bent sections nearest thereto and the upstream ends of said tubes being clear of the surrouding wall of said jacket. 